Hi, I think my 4x4 solenoid does not work properly. I checked it with the tube that goes to the 4x4 blocked off so I do not loose the air because I have a leak at the right wheel. ( My 4x4 does not work obviously)
The valve flickers when I select the 4x4 button but then after 15 to 30 seconds, it bleeds off by itself. It does not seem to hold. Is this normal?
I checked the price today, they want 124 dollars for it but the ford F150 is only 34 dollars. The 150 valve is a smaller unit and it has only 2 wire prung. The diesel one is bigger and has 3 wires to it. As the dealer told me, the F150 has two solenoid, I would use only one.
I think the valve only gives a go or no go for suction, then when we disengage the 4x4, it bleeds off the air for a short time to let the air come out of the 4x4 to disengage it, then it would relock the air so we still have the heater working and the accumulator to rebuild the vacuum. I wonder if the third wire would be to give a signal to momentarily disengage de 4x4.
You need to ask questions in the F-150 forum first and find out how the solenoids are supposed to work. If it's anything like the F-250, it is a pulse lock/unlock. There is not vacuum applied at all times. Vacuum is only applied during the lock and unlock cycles.
From what you describe, the F-150 solenoid will not work.
If the vacuum pump is always running, then you have a leak somewhere between the pump and the solenoid, or the solenoid itself. Try removing the solenoid hose and plugging it and see if the pump eventually stops. It might take a minute.